Learning and Generating Mixed States Prepared by Shallow Channel Circuits

Fuente: arXiv
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Hauptverfasser: Hu, Fangjun, Kokail, Christian, Kornjača, Milan, Lopes, Pedro L. S., Gong, Weiyuan, Wang, Sheng-Tao, Gao, Xun, Ostermann, Stefan
Format: Preprint
Veröffentlicht: 2026
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author Hu, Fangjun
Kokail, Christian
Kornjača, Milan
Lopes, Pedro L. S.
Gong, Weiyuan
Wang, Sheng-Tao
Gao, Xun
Ostermann, Stefan
author_facet Hu, Fangjun
Kokail, Christian
Kornjača, Milan
Lopes, Pedro L. S.
Gong, Weiyuan
Wang, Sheng-Tao
Gao, Xun
Ostermann, Stefan
contents Learning quantum states from measurement data is a central problem in quantum information and computational complexity. In this work, we study the problem of learning to generate mixed states on a finite-dimensional lattice. Motivated by recent developments in mixed state phases of matter, we focus on arbitrary states in the trivial phase. A state belongs to the trivial phase if there exists a shallow preparation channel circuit under which local reversibility is preserved throughout the preparation. We prove that any mixed state in this class can be efficiently learned from measurement access alone. Specifically, given copies of an unknown trivial phase mixed state, our algorithm outputs a shallow local channel circuit that approximately generates this state in trace distance. The sample complexity and runtime are polynomial (or quasi-polynomial) in the number of qubits, assuming constant (or polylogarithmic) circuit depth and gate locality. Importantly, the learner is not given the original preparation circuit and relies only on its existence. Our results provide a structural foundation for quantum generative models based on shallow channel circuits. In the classical limit, our framework also inspires an efficient algorithm for classical diffusion models using only a polynomial overhead of training and generation.
format Preprint
id arxiv_https___arxiv_org_abs_2604_01197
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Learning and Generating Mixed States Prepared by Shallow Channel Circuits
Hu, Fangjun
Kokail, Christian
Kornjača, Milan
Lopes, Pedro L. S.
Gong, Weiyuan
Wang, Sheng-Tao
Gao, Xun
Ostermann, Stefan
Quantum Physics
Statistical Mechanics
Computational Complexity
Machine Learning
Learning quantum states from measurement data is a central problem in quantum information and computational complexity. In this work, we study the problem of learning to generate mixed states on a finite-dimensional lattice. Motivated by recent developments in mixed state phases of matter, we focus on arbitrary states in the trivial phase. A state belongs to the trivial phase if there exists a shallow preparation channel circuit under which local reversibility is preserved throughout the preparation. We prove that any mixed state in this class can be efficiently learned from measurement access alone. Specifically, given copies of an unknown trivial phase mixed state, our algorithm outputs a shallow local channel circuit that approximately generates this state in trace distance. The sample complexity and runtime are polynomial (or quasi-polynomial) in the number of qubits, assuming constant (or polylogarithmic) circuit depth and gate locality. Importantly, the learner is not given the original preparation circuit and relies only on its existence. Our results provide a structural foundation for quantum generative models based on shallow channel circuits. In the classical limit, our framework also inspires an efficient algorithm for classical diffusion models using only a polynomial overhead of training and generation.
title Learning and Generating Mixed States Prepared by Shallow Channel Circuits
topic Quantum Physics
Statistical Mechanics
Computational Complexity
Machine Learning
url https://arxiv.org/abs/2604.01197